A disulfide bond has been introduced in the beta/alpha-barrel enzyme N-(5'-phosphoribosyl)anthranilate isomerase from Saccharomyces cerevisiae. The design of this disulfide bond was based on a model structure of this enzyme, built from the high-resolution crystal structure of the N-(5'-phosphoribosyl)anthranilate isomerase domain from Escherichia coli. The disulfide cross-link is spontaneously formed in vitro between residues 27 and 212, located in the structurally adjacent alpha-helices 1 and 8 of the outer helical ring of the beta/alpha-barrel. It creates a loop of 184 residues that account for 83% of the sequence of this enzyme, thus forming a quasi circular protein. The cross-linked mutant enzyme displays wild-type steady-state kinetic parameters. Measurements of the equilibrium constant for the reduction of this disulfide bond by 1,4-dithiothreitol show that its bond strength is comparable to that of other engineered protein disulfide bonds. The oxidized, cross-linked N-(5'-phosphoribosyl)anthranilate isomerase mutant is about 1.0 kcal/mol more stable than the wild-type enzyme, as estimated from its equilibrium unfolding transitions by guanidine hydrochloride. Study holds ProTherm entries: 4215, 4216 Extra Details: additive : EDTA(1 mM), disulfide bond; beta/alpha-barrel; quasi circular protein;,engineered protein
Submitter: Connie Wang
Submission Date: April 24, 2018, 8:24 p.m.
|Number of data points||2|
|Assays/Quantities/Protocols||Experimental Assay: ddG|
|Libraries||Mutations for sequence MSVINFTGSSGPLVKVCGLQSTEAAECALDSDADLLGIICVPNRKRTIDPVIARKISSLVKAYKNSSGTPKYLVGVFRNQPKEDVLALVNDYGIDIVQLHGDESWQEYQEFLGLPVIKRLVFPKDCNILLSAASQKPHSFIPLFDSEAGGTGELLDWNSISDWVGRQESPESLHFMLAGGLTPENVGDALRLNGVIGVDVSGGVETNGVKDSNKIANFVKNAKK|